This invention relates generally to containers and more particularly to bags or liners formed of flexible material.
Many granular and liquid products have been shipped and stored in large bulk bags or bulk containers with liners, which may contain as much as a ton or more of material. Some of these bulk bags are flexible, contain a liner, and when empty can be folded to a generally flat condition. One such flexible bag and liner is disclosed and claimed in U.S. Pat. No. 5,104,236. These flexible bags and liners for bulk containers, have been formed from a single tubular blank of material to form generally rectangular ends interconnected by generally rectangular side walls. When filled, these bags can be stacked one on top of another. For some applications, the bags may be made of a woven fabric and for other applications, a plastic film or sheet material. For some applications, particularly for storing liquids, a bag or liner of a liquid impervious film material is received in and reinforced and protected by bag of a woven fabric. Usually these bags have a spout in one or both ends for filling and emptying the bags.
Some such flexible bulk bags are formed by folding one or more blanks of flexible material to provide a pair of gusset panels folded inwardly and disposed between a pair of overlying flat panels. Heat seals or stitching along inclined lines forming triangular portions at one or both ends of the bag provide integral, rectilinear end walls of the bag interconnected by four sidewalls. Some bags include a spout extending from their upper end wall to facilitate filling and emptying the bag and have a completely closed bottom wall forming a so-called xe2x80x9cV-bottomxe2x80x9d bag wherein the bottom of the bag is generally V-shaped when the bag is gusseted and folded flat.
Desirably, the blanks of flexible material used to form the bulk bags may be provided in elongate rolls to facilitate manufacture of a plurality of bags. With bags having a spout at one end and a closed V-shaped opposite end it is preferable to form a plurality of bags on the rolls of material with the V-shaped wall of each bag adjacent to a V-shaped wall of an adjacent bag. So arranged the spout of each bag is connected to or adjacent to a spout of another adjacent bag on the roll of material. Bags can also be arranged with the V-shaped wall adjacent to the spout of the adjacent bag. After heat sealing adjacent V-shaped end walls, or adjacent V-shaped walls and spout, and removing the waste or scrap material between the adjacent bags, there is no material left between adjacent bags on the roll of material due at least in part to the heat seals leading to the apex of the V-shaped wall, separating the blank between the bags. This prevents subsequent processing equipment from pulling or advancing the roll of material for subsequent processing. Accordingly, bags of this type had to be separated from the roll of material along a straight line perpendicular to side edges of the blank to provide smaller, individual rectangular blanks that are individually processed to form at least the V-shaped wall of each bag. This increases the time, labor and cost to make the bags, reduces the ability to automate the manufacturing process and greatly reduces the efficiency of the manufacturing process.
A method of forming a plurality of interconnected bulk bags or liners with an interconnecting section of material between adjacent bags on a roll or blank of flexible material to permit the blank of material to be advanced for subsequent processing. The interconnecting section is defined at least in part by a separation line that permits scrap or waste material to be removed from the blank without removing the interconnecting section. This permits the bags to remain interconnected after they are formed so that they may be disposed on a roll or folded in a box for convenient shipping and handling of a plurality of bags. Desirably, perforations maybe provided between adjacent bags to facilitate removal of an individual bag from the remainder.
Preferably, closed ends of the bags are formed by heat sealing a gusseted blank of material along inclined lines forming so-called V-shaped end walls when the bags are folded flat. Waste or scrap material between the heat seal lines of adjacent V-shaped end walls of two adjacent bags on the blank may be removed without removing the interconnecting material between adjacent closed ends of the adjacent bags. To accomplish this, tear lines extend to the heat seal lines, which form the closed end of each bag to separate the waste material from the interconnecting section of material between the bags. Accordingly, when the waste material is removed by tearing or peeling along and outboard of the heat seal line of the closed end of the bag, such tear continues until it reaches and follows along the tear line to prevent removal of the interconnecting section between adjacent bags. Desirably, serration""s are provided in the interconnecting section between the adjacent bags to facilitate subsequent removal of the interconnecting section prior to use of the bags.
Objects, features and advantages of this invention include enabling substantially automated manufacture of a plurality of bags with a V-shaped end wall from one or more rolls or blanks of flexible material, permitting a plurality of bags to remain interconnected after forming so that they may be further processed, allowing a plurality of bags with a V-shaped end wall to be rolled up or otherwise manipulated for convenient shipping and handling prior to their use, facilitates manufacture of adjacent bags having adjacent V-shaped end walls and bags having a V-shaped end wall disposed adjacent to a spout of an adjoining bag, reduces the time, labor and cost to form a plurality of bulk bags, can be readily implemented with substantially conventional bag manufacturing machines, eliminates the need to separate individual bags from the blank to form closed ends of the bags, increases the efficiency of the bag forming machinery and process and is of relatively simple design.